Tool/software:
Hey dear TI engineer,
I’m using Lm5069 in my design i referenced the SNVA683 with some adjustment for my use case. i currently have a problem in SC startup sequence at 50-48v the fault timer doesn’t charge and the gate get stuck in 4V for long time burning the MOSFET. (Figure 1 & 2)
I tried many thing such as shorter fault timer by decreasing the fault timer capacitor to be in safe side of the SOA graph and decreasing the Power limit resistor added more input capacitance but that did not help furthermore the voltages that worked before the gate get stuck oscillating around 4v and the timer got extended.(figure 3-8)
Note: you can see the wanted behavior in figure 9 with 39k ohm pwr resistor and 10nF fault timer capacitor.(original design prameters)
After that i tried changing the Rsense value to bigger value, from 1.3m ohm to about 2m ohm and lastly to 5 m ohm, to know if its current sense problem or something else. Once again i got the same problem kind of problem at lower voltage level, the timer not charging and the gate stuck on 4V until the MOSFET burns figure 10-11 you can see wanted behavior in figure 12-13 , 5m ohm experiment figure 14-16.
My schematic and calculator tool excel with all the relevant scope snap shots is in the attached zip file.
Best regards,
Daniel
